Noise associated with the use of a firearm is, in general, attributed to two factors. The first factor is associated with the velocity of the bullet. If the bullet is traveling hypersonically (i.e., faster than the speed of sound), the bullet will pass through the slower moving sound wave preceding it, thus creating a relatively small sonic boom, similar to the sonic boom of a supersonic aircraft passing through its sound wave. The second factor is associated with the rapid expansion of propellant gas produced when the powder inside the bullet cartridge ignites. When the propellant gas rapidly expands and collides with cooler air, in and around the muzzle of the firearm, a loud bang sound occurs. Firearm noise suppression devices (hereafter “noise suppression devices”) are employed to reduce noise attributable to the second factor identified above. Noise suppression devices have been in use at least since the late nineteenth century.
FIG. 1 is a cross-sectional view of a contemporary noise suppression device 100. As illustrated, noise suppression device 100 includes an inner structure or core 105 and an outer structure 110. Typically, the core 105 and the outer structure 110 are manufactured independent of each other. Subsequently, the core 105 is inserted in and secured to the outer structure 110. Securing the inner structure 105 to the outer structure 110 may be achieved by welding (e.g., spot welding) the former to the latter. Together, the core 105 and outer structure 110 are often referred to as a “can.”
The core 105, in turn, comprises a plurality of linearly arranged segments that together form a plurality of compartments 105a through 105f, wherein adjacent compartments are separated by a corresponding baffle 115a through 115e. It is very common to manufacture each segment separately and then attach the segments together, e.g., by welding the segments, to form the aforementioned linear arrangement, as suggested by the weld joints or seams that appear between each of the segments in FIG. 1 (see e.g., seams 120a, 120b, 120c, 120d and 120e). Although it may be common to manufacture each of the aforementioned segments separately and then subsequently attach them together, it is also known to manufacture the segments as a single, integral unit. Such a unit is referred to as a monolithic core. The monolithic core is then inserted in and secured to the outer structure 110, as previously described.
Additionally, the distal end of the core 105 comprises an end cap segment 125, while the proximal end of the core 105 comprises a base cap segment 130. As illustrated, there is an opening formed through each of the baffles 115a through 115e, the end cap structure 125 and the base cap structure 130, along a longitudinal centerline Y, which defines the path through the noise suppression device 100 traveled by each fired bullet.
Although it is not shown in FIG. 1, the proximal end of the noise suppression device 100 would comprise an attachment structure. The attachment structure would be configured to attach the noise suppression device 100 to a complimentary structure associated with the muzzle of the firearm.
As mentioned above, noise suppression devices reduce the noise associated with the rapid expansion of propellant gas when the powder inside the bullet cartridge ignites and the propellant gas subsequently collides with cooler air in and around the muzzle of the firearm. In general, noise suppression devices reduce the noise by slowing the propellant gas, thus allowing the propellant gas to expand more gradually and cool before it collides with the air in and around the muzzle of the firearm.
Thus, with respect to the noise suppression device 100 in FIG. 1, the bullet will first pass from the muzzle of the firearm into the first expansion chamber 135. It should be noted that this first chamber is often called a blast chamber or blast baffle. The first expansion chamber 135 allows the propellant gas to expand and cool, thereby reducing the amount of energy associated with the gas. The bullet then successively passes through the openings in each of the baffles 115a through 115e, wherein the baffles further deflect, divert and slow the propellant gas. By the time the bullet and gas exit the opening through the end cap structure 125 at the distal end of the noise suppression device 100, the gas has already substantially slowed, expanded and cooled, thus reducing the noise associated with the gas colliding with the cooler air in and around the distal end of the noise suppression device 100.
Conventional noise suppression devices are typically constructed from steel, aluminum, titanium or other metals or metal alloys. Metals generally have good thermal conductivity characteristics. Therefore, metal noise suppression devices can better absorb the heat that is produced by the rapidly expanding propellant gas. This ability to better absorb the heat helps to more quickly cool the propellant gas, thereby reducing both the temperature and volume of the gas, and in turn, the resulting noise when the gas collides with the ambient air.
Despite the fact that noise suppression devices have been in use for well over 100 years, and numerous improvements have been made over this time period, there are still many disadvantages associated with conventional noise suppression devices. For example, the noise suppression device 100 described and illustrated above inherently has reliability issues in that each welding joint or seam increases the probability of structural failure due to the high levels of pressure associated with the propellant gas inside the device.
The use of metal also leads to certain disadvantages. Metal is costly and manufacturing a noise suppression device, such as noise suppression device 100, is somewhat complex. Consequently, manufacturers may be discouraged to make and customers may be reluctant to purchase customized noise suppression devices, as customized noise suppression devices are likely to be even more costly and more complex to manufacture. An example of a customized noise suppression device may be one that is designed and constructed to operate in conjunction with, or at least not interfere with a particular gun sight.
Further with regard to the use of metal, the aforementioned thermal conductivity may actually be undesirable in certain situations. For instance, after firing the weapon, the noise suppression device may be very hot due to the fact that the metal is efficient at absorbing the heat associated with the propellant gas. This is particularly true if the weapon is fired repeatedly. And, if the noise suppression device is hot, it may be very difficult for the user to remove it from the weapon until it cools. This may be unacceptable if the user needs to quickly replace the noise suppression device for another. In a military environment, a hot noise suppression device may also be highly visible to enemy combatants using infrared technology, thus exposing the user to greater risk.
Yet another disadvantage associated with metal noise suppression devices is that these noise suppression devices are considered weapons in and of themselves, separate and apart from the firearm to which they may be attached. Thus, they are regulated under the National Firearms Act (1934)(NFA). As such, these devices must be separately marked and registered, and they cannot simply be discarded when they are worn or otherwise fail to function adequately. This is true, even if the devices are being used in a war zone or military environment.
Therefore, despite the many improvements that have been effectuated over the decades, additional design features and manufacturing techniques are warranted to improve the reliability, enhance the noise reduction, reduce the costs, facilitate customization and eliminate the restriction on disposability of conventional noise suppression devices. The present invention offers a number of improvements that address these concerns.